P0462: How to Diagnose & Fix — Fuel Level Sensor 'A' Circuit Low Input

On 2007–2014 Sierra 3500HD models, the fuel tank mounting straps and the fuel level sender unit are prone to corrosion, causing inaccurate fuel gauge readings and in some cases complete sender failure. NHTSA complaint data documents numerous owners reporting sudden fuel gauge drops to empty or erratic readings unrelated to actual fuel level. The plastic float arm on the sender can also crack, exacerbating the problem.

Fuel system complaints are the single largest NHTSA category on the early P2 S60 (roughly 74 complaints on the 2002 and 92 on the 2001). Two distinct parts fail. The fuel level sender's resistive card wears where the wiper arm sweeps, so the gauge reads erratically, sticks full, or drops to empty with a full tank and triggers the low-fuel warning. Separately, the in-tank fuel pump module loses pressure with age and heat, producing long cranking, hot-restart no-starts, stumbling under load, and eventual stalling. Because the pump and sender share one tank-top module, a failure of either usually means dropping or accessing the same assembly.

The in-tank fuel level sending unit (float arm and variable-resistor card, part of the fuel pump module) wears out and gives false readings — commonly reading full then dropping to empty, sticking, or bouncing. On OBD-II trucks it sets P0463/P0462. It is one of the most-searched Ram gauge complaints and is separate from the instrument-cluster fault.

Tiguan owners across both generations report the fuel gauge reading wrong: sticking at full for a long time after fill-up then dropping quickly, showing three-quarters with an empty tank, or failing to reset at all after refueling. On the first-generation car the cause is the in-tank fuel level sender's resistive track, which is attacked by sulfur compounds in fuel and wears at commonly used positions; the sender is part of the fuel pump/sending-unit assembly. On 2019-2023 MQB cars the same complaint sets P0461 (fuel level sensor range/performance) and Volkswagen's TSB 01-23-06 says to update the engine control software before replacing any hardware, because a calibration error rather than a bad sender is often the cause.

The combined in-tank fuel pump / level-sender module on the WJ Grand Cherokee wears out with age: the pump loses pressure (needs ~49-58 psi) causing crank-no-start or hot stalling, while the integrated sending-unit float/resistor card fails causing erratic or stuck fuel-gauge readings. Both a no-start and a jumpy fuel gauge are heavily searched WJ complaints and often the same module.